Gas-insulated switchgear owners face easy-to-miss, CARB-enforced emissions requirements.

By JP Brisson, Aron Potash, R. Andrew Westgate, Kimberly D. Farbota, and Christopher C. Antonacci

Since 2011, the California Air Resources Board (CARB) has regulated sulfur hexafluoride (SF6) emissions from gas-insulated switchgears (GIS). CARB’s SF6 Regulation applies to all entities that own GIS, including many entities that do not otherwise emit and report greenhouse gas (GHG) emissions such as wind farms, solar parks, and geothermal plants. Accordingly, some companies may not have realized that they are subject to the SF6 requirements. The SF6 Regulation includes emission rate limits, mandatory operating procedures, and recordkeeping and reporting requirements, as well as providing for monetary penalties in the event of a violation.

Background on SF6 Gases

SF6 is used in GIS equipment to protect electrical power plants and distribution systems by insulating circuits and interrupting electric currents. Since the initial use of SF6 in the 1950s, SF6-containing circuit breakers, transformers, switches, fuses, and other equipment have been used regularly because SF6 is non-flammable, non-corrosive, non-toxic, and an effective arc suppressant, which allows SF6 equipment to have a small footprint and be relatively low maintenance. GIS containing SF6 gases are typically found in most if not all substations and at many power generating facilities, including natural gas plants, wind farms, solar parks, and geothermal plants.

Although SF6 is non-toxic, the gas is one of the most potent GHGs with a global warming potential of 23,900 and an atmospheric lifetime of 3,200 years. For comparison, carbon dioxide has a global warming potential of 1. Consequently, during a 100-year period, a pound of SF6 would trap 23,900 times the amount of infrared radiation that a pound of CO2 would trap.

Regulation of SF6 Gases in California

CARB first took action to regulate SF6 in 2007, designating the reduction of SF6 emissions from electricity transmission and distribution equipment a high priority “early action measure” under the California Global Warming Solutions Act of 2006 (AB 32). In 2009 and 2010, CARB conducted a rulemaking to develop the regulation for monitoring and limiting SF6 emissions.

The SF6 Regulation took effect in 2011 and is codified in the same subchapter of the California Health and Safety Code as CARB’s mandatory GHG reporting and cap-and-trade regulations. Such GHG reporting and cap-and trade regulations apply to sources that emit more than 25,000 (in some cases 10,000) tonnes of GHG annually. Accordingly, the GHG reporting and cap-and trade regulations apply primarily to large industrial, manufacturing, refining, and fossil fuel plants. The SF6 Regulation, however, does not contain an emissions threshold and therefore applies far more broadly. For example, California renewable energy providers that own SF6 switchgear are not required to report their GHG emissions, but they are subject to the SF6 Regulation. The SF6 Regulation applies to all owners of SF6-insulated switchgear — even if an owner only has one piece of equipment and no GHG emissions. As such, switchgear owners can easily miss the SF6 Regulation.

SF6 Regulation Requirements

The SF6 Regulation contains a number of requirements, which have applied since January 1, 2011. Under these requirements, all GIS owners must:

  • Limit the rate of SF6 emissions
  • Establish and adhere to written procedures to track gas containers as they leave and enter storage
  • Follow certain recordkeeping requirements, including for GIS equipment and gas containers
  • Submit annual reports to CARB describing facility operations and SF6 emissions

CARB actively enforces the SF6 Regulation in the same manner in which it enforces other regulations, and numerous companies have entered into settlement agreements with the agency following alleged violations of the SF6 emission rate limits and reporting requirements. CARB has also conducted numerous site inspections to enforce the regulation.